In previously known devices for monitoring exposure to ultraviolet radiation, or dosimeters, such as disclosed in U.S. Pat. Nos. 4,428,050, 4,229,733, 4,608,492, 3,878,496, 3,710,115 and 4,348,664, it has been known to sense ultraviolet radiation impinging upon a body and provide an alarm when the cumulative amount of radiation to which the body has been exposed attains a threshold level beyond which erythema may occur.
Most of these devices, however, only have regard for the immediate effects of exposure of the skin to ultraviolet radiation and do not consider the delayed or tanning effect of the ultraviolet radiation upon the skin which vary dependent upon the accumulated exposures of the skin to ultraviolet radiation in the past. Accordingly, such devices are only applicable to persons that do not acquire a tan from successive exposures of the skin to ultraviolet radiation, since these devices are unable to even develop a weekly tanning profile.
Other devices which may have the ability to provide a tanning profile are reliant upon the user manually programming the device after each exposure of the skin to ultraviolet radiation and hence do not provide an automatic generation of tanning profile with minimal user interaction. Devices such as those disclosed in Pellegrino et al (U.S. Pat. No. 4,428,050) are software oriented involving complex algorithms which perform the necessary calculations to determine radiation dosage limits for persons exposed to ultraviolet radiation after the input of relatively detailed information to the computer operating the same. Such a device is not practical for all-purpose use and does not perform real-time monitoring of the exposure of a body to ultraviolet radiation and real-time determination of the tanning effect of the radiation, but rather establishes a program for a person to follow for tanning after the specification of a large number of input parameters by the user.